On 11 July 2013, Bostock joined Royal Antwerp FC in the Belgian second division under the tutelage of manager Jimmy Floyd Hasslebaink. Despite scoring just one goal he flourished at Antwerp providing 16 assists in his first season and soon became a fans favourite helping the team to finish 6th in the league narrowly missing out on the playoffs. His strong performances earned him a move to newly relegated side Oud-Heverlee Leuven, where he continued to blossom. In his second season in Belgium, Bostock went on to help his new side OHL win promotion via the play offs. Along the way he scooped the Proximus Player of the Season Award after scoring 13 goals and providing 19 assists.
In the 2015/16 season Bostock quickly made a name for himself in the Jupiler Pro League. He earned himself the nickname “Jonenka’ after converting 3 of his 5 penalties by chipping the keeper. John had a largely successful campaign in his debut season solidifying himself as one of the leagues best midfielders in the Belgian top flight notching 7 goals along with 4 assists.